Home – Home – Jornals – Chemistry for Sustainable Development 2017 number 3

The precipitation of bismuth (III) from nitric acid solutions depending on the concentration of malate ions, process temperature, pH values of solutions upon the addition of an optically active L(-)-isomer and racemic DL-malic acid was studied by X-ray phase analysis (XPA) methods, IR and Raman scattering spectroscopy (RSS), thermogravimetry and chemical analysis. It was demonstrated that bismuth malate monohydrate with a composition of BiC₄H₃O₅ x Н₂О was precipitated when adding L(-)-malic acid into nitric acid solutions, and in case of the addition of DL-malic acid, a compound with a composition of BiC₄H₃O₅ x 0.5Н₂О is formed. Coordination of the bismuth cation with malic acid anions was studied by spectroscopic methods. It was found that malic acid residue in the compounds under study was thrice deprotonated, and their bond with the bismuth cations was carried out through all functional groups of malic acid, The conducted research of obtained bismuth malate demonstrated that L -malate samples in comparison with bismuth DL -malate were homogeneous by the particle size distribution, which does not require the additional cost on grinding the sample to a homogeneous state when using it as a medicinal substance, and an increase in process temperature allows obtaining more fine-grained powders. The advisability of the preparation of bismuth malate for medical purposes from bismuth metal was demonstrated with preliminary oxidation of the latter with air oxygen, dissolution of the resulting oxide in nitric acid (1 : 1) and precipitation of bismuth (III) malate by the addition of a bismuth-containing solution to a sodium malate solution with a molar ratio of malate ions to bismuth of 1.1-1.2 and process temperature of (60±10) °С.